1. Field of the Invention
The invention relates to inspection port systems that facilitate internal inspection of gas turbine engines. More particularly, the invention relates to a standardized gas turbine inspection port system with port and port plug that are utilized throughout the engine. Preferably the each inspection location on the gas turbine that utilizes the standardized inspection port system has identical component dimensions and are oriented along common axial and radial positions (e.g., 6 o'clock and/or 12 o'clock radial orientation) to facilitate internal inspection of all corresponding blade/vanes that share a common row about the entire turbine casing circumference.
2. Description of the Prior Art
Industrial gas turbine engines are often equipped with inspection port systems that facilitate inspection instrument access to turbine internal components from the exterior of the turbine casing. U.S. Pat. No. 3,936,217, the entire contents of which is incorporated by reference herein, shows a typical inspection port system with a cylindrical inspection port, mating port plug that seals the inspection port, and external flanged port member projection outside the turbine casing (also referred to as a stub tube tube). The port plug and cylindrical inspection port have mating complimentary interlocking lug pins and J slots that function as a securing mechanism to retain the plug with the port. Another known plug/port securing mechanism are mating male and female threads.
Port plugs are inserted into the gas turbine inspection port system by advancing the elongated plug into the turbine casing through the stub tube. Thereafter the plug tip is inserted into the relatively narrow diameter inspection port tube along a narrow alignment path, which is analogous to threading a needle, while taking care not to drop the plug into the turbine casing.
Individual inspection port system access locations and dimensions on a gas turbine engine vary among engine designs. For example, different inspection rows within a gas turbine compressor or combustor section often have different length dimensions between the gas turbine casing inspection hole and the stub tube flange, as well as different port diameters. Often the flange dimension and configuration for each respective stub tube will vary on the same turbine and radial position about the case circumference will also vary from one row to another or among different turbine models. Lack of uniformity raises inspection service challenges. For example, an inspection tool suitable for one inspection row may be too large in diameter or length for a different inspection port system access point in the same or in a different inspection row. Length variances between a stub tube flange and gas turbine casing inspection hole often requires a service technician to configure inspection instruments differently from row to row so that instrument insertion distance can be correlated with instrument orientation within the turbine casing. Different stub tube flange configurations and/or dimensions requires different instrument anchoring or other securement methods relative to the turbine casing or perhaps use of adapter flanges.
Thus, a need exists in the art for a standardized gas turbine engine inspection port system that enhances engine inspection and maintenance by providing preferably identically dimensioned access paths and external anchoring flanges for inspection tool and other service tool insertion into the gas turbine engine, with system ports arrayed along common aligned locations in a plurality of turbine blade/vane rows.
An additional need exists for an inspection port plug and plug installation/removal service method that facilitates easy plug insertion and alignment into an inspection port system inspection port body, with reliable sealing of the gas turbine casing inspection hole.
Another need exists for an inspection port plug and plug installation/removal service method that reduces likelihood of inadvertently dropping a port plug into the gas turbine casing during removal or installation.